Vintage HiFi Audio Forum
Audio Discussion => DIY => Topic started by: Tiga on February 28, 2010, 04:29:32 PM
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I have reason to believe that one or several of the resistors on my Sansui 9090 driver board are out of tolerance and need to be replaced. From what I've read this is a common problem with this model.
I've never done this sort of work before and I don't have much time to learn right now unfortunately. Any recommendations on who might be able to do this repair at a reasonable cost? There is probably around 50 resistors on this board that would need to be checked and replaced as necessary. Thoughts on what this should cost? Thanks everyone!
Dave
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Tommy, or Phils tv in Bellvue
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Why do you think it is a resistor?
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It is a lot more likely that capacitors need to be replaced.
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It is a lot more likely that capacitors need to be replaced.
I concur. That is the first place to start. More than likely, the resistors and drivers are fine. What are the symptoms you have?
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The unit goes into protection mode immediately when you power on - once you remove the driver board it comes out of protection. Doing some internet research shows this issue is pretty common with this model and the majority of the time it's the resistors on the board that fail open or go way out of tolerance.
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It sounds like output transistors may also be a possible problem. Check for a shorted output.
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Does testing the transistor require special equipment to test? Another question - if the output transistors are bad would the unit come out of protection when the driver board was removed? Sorry for the newb questions. Thanks guys.
Dave
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Yes, removing the driver board can make the unit come out of protection. You can test with a meter.